In a network, in particular in a wireless network, it is required to keep every node updated with the currently used value of network configuration parameters to maintain a correct operation for each node of the network. Indeed, it is possible that, due to unscheduled events, like a change in the interference spectrum or location, or due to scheduled events, like a periodic change of a cryptographic key, a maintenance entity needs to communicate a new value for a network configuration parameter, like a channel identifier, a network identifier, a node identifier or role, an identifier of a new coordinator/maintenance entity inside the network, a cryptographic key, a key descriptor or a key seed.
However, in some networks, there can be some nodes that are limited in terms of reception opportunities. As an illustration, in a ZigBee network, there may be ZigBee Green Power Devices (ZGPDs), which harvest the energy from their environment or have very limited battery and thus unpredictable receiving behaviour. For example, a ZGPD can be a battery-less switch with electro-mechanical energy harvester that can only receive for a short time once it is actuated by a user and has transmitted its signal. Another example of a ZGPD is a periodically-reporting sensor, harvesting energy from its environment, e.g. by means of a photovoltaic cell. However, the presence in the environment of this energy is not predictable and the sensor may not be able to report anymore for a period of time. Because of their energy budget limitations, those devices are also not able to discover the new parameters via an active search.
Given that these devices cannot receive a configuration signal at each point in time, if a reconfiguration of the network occurs in the interval between two reception opportunities of a limited device, this limited device would be unaware of the change in the parameter value.
This is likely to cause the limited device to be excluded from the network, since it would still use the previous version of the network parameters and thus its messages are likely not to be received, or if received—likely to be dropped—by its communication peers which have been updated. For the limited device to be reintegrated in the network, it requires a special process which is very likely to require manual intervention from the user, can be long and is thus a large maintenance burden.
Moreover, the duration of the reception opportunities in operation may be very short, in particular after transmission of data packets. For example, a ZigBee Green Power Device indicates the reception capability in the regular frame it sends (upon user/sensor/application trigger), by setting an RxAfterTx flag. 5 ms after this transmission, the ZGPD opens its radio for reception, for at least 0.576 ms, corresponding to the shortest Green Power Device Frame. This duration is not sufficient e.g. to receive a packet containing a new key.